1. Field of the Invention
The invention relates to a compound thermal insulating system that can be attached to a building wall with a light-absorbent external wall surface, which system include an at least partially transparent insulating material protected externally from the effects of weather.
2. Description of the Prior Art
In compound thermal insulating systems known to the prior art (EP-B 0 123 091), a transparent external coating for the absorption of solar energy is provided on the outside of the insulating material in the form of foils or disks of silicate or acrylic glass, particularly pressed glass. Such application occurs in the form of prefabricated units which resemble windows and which are bound in aluminum frames. These units can hardly be used in the renovation of older structures. In the case of new structures their use must be planned as early as the drafting stage. In addition, it is impossible to avoid partition lines with these panel shaped, brick-shaped, or belt-shaped panes. Production of this kind of external facing is not only very complicated, time-consuming, but expensive. It is also very difficult to give this transparent outer coating the necessary strength and stability to guarantee these properties over long periods of time. In addition, the range of architectural design permitted by this compound thermal insulating system is very limited, particularly when it is employed in geometrically complex parts of a facade. Another problem is the fact that, due to the high transparency, a transmission ratio of 50% and sometime more, results so what shading in the form of blinds, shades, or the like must be provided--which devices must, be set by a regulating device or must be continuously manually adjusted. Due to the water vapor permeability of the employed panes, considerable problems with condensation arise in the case of temperature fluctuations, particularly when outside temperatures drop below the freezing point.